<script>
    window.onload=function (ev) {
        var userId = xhTool.getQuery('userId');
        $.ajax({
            url:baseUrl+'school/getLoginQR',
            data:{userId: userId},
            dataType:'json',
            method:'post',
            success:function (res) {
                $('#loginQR').attr('src' , res.msg);
            }
        })
    }
</script>
<style>
    body,html{
        height: 100%;
    }
</style>
<div style="height: 100%;width: 100%;text-align: center; display: table;">
    <span style="display: table-cell; vertical-align: middle; "><img id="loginQR" style="display: inline-block"/></span>
</div>
